In the three-dimensional scanning of large objects, the current methods used to perform best fit alignment scans from large data sets collected from high speed, long range laser scanners are largely inefficient. No accurate method to integrate the data from the scans with data from other types of scanners and single-point measurement devices is known to exist. The current solution to best fitting of adjacent scans may involve location of three or more common points in the data for the initial fit and best fitting the data using overlapping data. Currently, large spherical artifacts are used which allow data to slip along incomplete spherical surfaces due to multiple possible fit solutions. However, it may be difficult to pick common points along the spherical surface of the artifacts. Scan data may be most accurate when the laser beam is perpendicular to the artifact surface. Perpendicularity, however, diminishes rapidly along a spherical surface of the artifact. To position the aligned scans to the global coordinate system, it may be required that features such as hole center lines be extracted from the scan data to perform the transformation. Spherical artifacts may lack provisions to integrate with other scanning and measurement devices. Alignment of scan or measurement data to a global coordinate system may be performed manually with questionable accuracy.
Locating common points in large scans may be difficult especially when features are similar throughout the data. When commercial best fit alignment software attempts to align the scans using overlapping data, alignment error may be magnified as the distance from the overlapping area increases. The limited accuracy achieved with the spherical artifacts may do little to alleviate the fit error. It may be a laborious process to attempt to extract discrete features such as hole centerlines or “golden rivet locations” from scan data. Accuracy of the alignment to the global coordinate may be highly suspect to the accuracy of the feature extraction and due to the lack of fitting the data to the entire envelope of the subject.
Therefore, a prismatic alignment artifact is needed which may facilitate recognition of common points in adjacent scans for initial alignment of the scan data; which may facilitate measurement of artifact locations with high-precision devices to allow accurate positive location relative to a global coordinate system; which may facilitate ease in integrating data from multiple scanner types; and which may be easier to mount to a surface due to its shape.